Lighting fixture with detachable ballast

ABSTRACT

A fluorescent lighting fixture incorporating a receptacle provided with a readily replaceable ballast unit that may be safely connected to and disconnected from the circuit of the fixture while it is energized. A two-part electrical connector unit is provided in the circuit, one part being fixed to the receptacle and the other part mounted together with the ballast as a replaceable component arranged to engage and disengage the connector unit parts as an incident of installation and removal of the replaceable component. Preferably, the connector unit parts comprise a male plug and complemental female socket specially arranged to cause the respective high voltage contacts thereof to become engaged prior to, and disengaged subsequent to, engagement of the respective low voltage contacts thereof during installation and removal of the replaceable component.

United States Patent lnventors Appl. No. Filed Patented Assignee LIGHTING FIXTURE WITH DETACHABLE Primary'ExaminerSamuel S. Matthews Assistant Examiner-Robert P. Greiner Att0rneysChanning L. Richards, Dalbert U. Shefte and Francis M. Pinckney BALLAST 3 Claims, 9 Drawin F' s.

g ABSTRACT: A fluorescent lighting fixture incorporating a U.S. receptacle provided a readily re laceable ballast unit that 240/11-4, 339/ 1 84 may be safely connected to and disconnected from the circuit [5 Int.

of the fixgure while it is energized, A two part electrical con- "0 3 nector unit is provided in the circuit, one part being fixed to' [50] Field of Search 240/5l.l1, the receptacle and the other part mounted together with the 11-4, 9/ ballast as a replaceable component arranged to engage and disengage the connector unit parts as an incident of installal l References cued tion and removal of the re laceable com onent. Preferabl P P Y UNITED STATES PATE the connector unit parts comprise a male plug and comple- 2,494,428 1/1950 Buck 240/5l.11(X) mental female socket specially arranged to cause the respec- 2,702,378 2/1955 Talty 240/5 1 .1 1(X) tive high voltage contacts thereof to become engaged prior to, 2,988,633 6/1961 Rosenfield. 240/5l.1 1(X) and disengaged subsequent to, engagement of the respective 3,040,170 6/1962 Chwan 250/51.11 low voltage contacts thereof during installation and removal 3,135,822 6/1964 Baran et al 240 5 1.1 1 X of the replaceable component.

146 m be be 4 L l l m z 1 2 l z r162 16a, '1 u A 162 1 122 PATENTED MAR 9 |97l SHEET 2 [IF 3 LIGHTING FIXTURE WITH DETACHABLE BALLAST BACKGROUND OF THE INVENTION A conventional fluorescent lighting fixture is provided with a ballast that acts to raise substantially the input voltage thereto, the input voltage being impressed on the low voltage side of the fluorescent lamps fitted in the lighting fixture and the raised voltage being impressed on the high voltage side of the lamps whereby a sufficient voltage potential is realized across the lamp to cause it to light. The ballast is normally integrally fixed in the receptacle of the lighting fixture, and the high and low sides of the ballast are wired directly into the circuit of the lighting fixture.

It is necessary from time to time to replace burned out or otherwise defective ballasts. I-Ieretofore, the replacement of a ballast had to be done by a workman having at least a minimum amount of experience in electrical work, and-it involved'a time'consuming operation which included the steps of disassembling a substantial portion of the lighting fixture to gain access to the ballast, disconnecting the ballast from its mounting and from the electrical lines leading to and from the ballast, and then connecting the new ballast in place and reassembling the lighting fixture. In addition, since fluorescent lighting fixtures are often electrically connected in banks on one main circuit, the replacement of a ballast in one of these fixtures included the inconvenience of having the entire bank temporarily out of service because the main circuit had to be deenergized to avoid exposing the workman to live wires during the replacement operation. By substantial contrast, the present invention provides a unique arrangement by which a ballast can be replaced quickly and safely in the energized circuit of a lighting fixture without significant disassembly of the fixture and without having to connect or disconnect the ballast from its mounting and the electrical lines leading thereto.

SUMMARY OF THE INVENTION This unique arrangement comprises a fluorescent lighting fixture in which a two-part electrical connector unit is interposed in the main line connection of the lighting fixture, one connector unit part being fixed in relation to the receptacle of the lighting fixture and the other connector unit part being associated with the ballast as a separable component supported with a disposition that respectively engages and disengages the fixed and associated connector unit parts as an incident of installation and removal of the ballast and associated connector unit part on and from the support thereof.

In the disclosed embodiment of the present invention, the ballast and the associated connector unit part are secured to a mounting plate which is supported in the lighting fixture receptacle by spaced retaining grooves which slidably receive opposed side edges of the mounting plate to permit selective attachment an detachment thereof for installing and removing the ballast and associated connector unit part secured to the mounting plate. Additionally, the lighting fixture receptacle is provided with an access opening adjacent the retaining grooves to permit the mounting plate, with the ballast and the associated connector unit part secured thereto, to be passed readily into and out of the receptacle without disassembly of the lighting fixture, and a removable cover member is positioned over the access opening to enclose the receptacle when the mounting plate is properly in place.

In some types of fluorescent lighting fixtures to which the present invention is applicable, the voltage impressed on the high voltage side of the fluorescent lamp by the ballast is very high (e.g., 785 volts) and, as a consequence, a potentially dangerous situation may be created at the respective contacts of the connector unit parts which carry this high voltage because the voltage potential across the contacts immediately before engagement and after disengagement thereof may be sufficient to cause current arcing thereat. Therefore, in accordance with a further feature of the present invention, the two-part connector unit includes an electrical contact arrangement which causes the high voltage contacts of the respective connector unit parts to become engaged prior to engagement of the low voltage contacts during installation of the ballast, and to become disengaged subsequent to disengagement of the low voltage contacts during removal of the ballast whereby the high voltage contacts are always engaged and disengaged while the lighting fixture current is open at the low voltage contacts.

In accordance with the preferred embodiment of the present invention, one of the connector unit parts comprises a male plug provided with extending blades of equal length forming high and low voltage contacts, and the other connector unit part comprises a female socket having blade receiving slots containing high and low voltage contacts, respectively, with the low voltage contact having a spacing from the blade receiving end of its slot that exceeds a corresponding spacing of the high voltage contact so that the respective high voltage contacts of the male plug and female socket will always be engaged first and disengaged last. In addition, the blades and slots may be specially shaped so that the slots will only receive a blade which will connect, respectively, the high voltage contacts and the low voltage contacts of the connector unit parts.

BRIEF DESCRIPTION OF TI'IE'DRAWINGS FIG. 1 is a perspective view of a typical fluorescent lighting fixture incorporating a detachable ballast in accordance with the present invention;

FIG. 2 is a plan view of a portion of the upper receptacle of a lighting fixture illustrating the ballast in an attached position;

FIG. 3 is a view similar to FIG. 2 and illustrating the ballast in a detached position;

FIG. 4 is a front elevation of the upper receptacle portion illustrated in FIG. 2;

FIG. 5 is an end view of the upper receptacle portion of a lighting fixture like that illustrated in FIG. 1;

FIG. 6 is a detail view, partially in section, of a two-part electrical connector unit according to the present invention;

FIG. 7 is an enlarged elevation view taken along line 7-7 in FIG. 6;

FIG. 8 is a wiring diagram of a lighting fixture and ballast according to the preferred embodiment of the present invention; and

FIG. 9 is a wiring diagram of a lighting fixture and ballast according to another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Looking now in detail at the accompanying drawings, FIG. 1 illustrates a typical slimline lighting fixture 20 including a receptacle 22 fitted with a pair of conventional fluorescent lamps 24, 24'. The upper portion of the receptacle 22 has a bottom wall 28, and a sidewall 30 formed with an access opening 32 over which is disposed a removable cover plate 34 held in place by screws 36. Secured to the bottom wall 2%, adjacent the access opening 32, are a pair of spaced retaining plates 38 held inplace by screws 40 and including, respectively, facing flanges 42 spaced vertically from the bottom wall 23 and extending laterally with respect thereto to provide spaced retaining grooves (see FIGS. 2 and 4) extending inwardly from the access opening 32. Also secured to the bottom wall 28 is an upstanding bracket member 44 in which a pair of female sockets 465, 46 are mounted. v

. The ballast 48 for the lighting fixture 20 is mounted by bolts 50 to a mounting plate 52 having a lengthwise dimension such that the opposed side edge portions 54 thereof may be slidably received in the grooves formed by the retaining plate flanges 42. Also flxed to the mounting plate 52 is an upstanding bracket member 56 in which a pair of male plugs 58, 58' are mounted, the upstanding bracket member 56 being located on the mounting plate 52 so that it will be disposed adjacent the corresponding bracket member 44 with the male plugs 58, 58 engaging the female sockets 46, 46, respectively, when the side edge portions 54 of the mounting plate 52 are received by the retaining plate flanges 42 as best seen in FIGS. 2 and 5.

The electrical line connections for the lighting fixture are shown in the wiring diagram illustrated in FIG. 2 which includes a primary, low voltagecircuit 60 leading from one line L of the main circuit through the low voltage side of one of the lamps 24, then through engaging contacts of a female socket and complemental male plug 58, respectively, and then to the low voltage side of the ballast 48. The low voltage circuit continues from the ballast 48 through engaging contacts'of the other female socket 46' and complemental male plug 58', respectively, then through the low voltage side of the other lamp 24' and back to the other line L of the main circuit. The secondary, high voltage circuit 22 comprises a line leading from the high voltage side of the ballast 48 through the remaining engaging contacts of the female socket 46 and male plug 58, respectively, and then to the high voltage side of one of the lamps 24' to impress a high voltage thereon. The high voltage circuit 62 similarly includes another line leading from the high voltage side of the ballast, through the remaining engaging contacts of the other male plug 58 and complemental female socket 46, and then to the high voltage side of the other lamp 24 to impress a high voltage thereon.

Thus, the lighting fixture 20 of the present invention is provided with an electrical circuit having interposed therein a disengageable two-part electrical connector unit, one part being the female sockets 46, 46' that are fixed in relation to the receptacle 22 and the lamps 24, 24, and the other part being the male plugs'58, 58' that are fixed on the mounting plate 52 together with the'ballast 48 to form a separable component which will respectively engage and disengage the female sockets 46, 46 with the male plugs 58, 58' as an incident ofinstallation and removal of this separable component.

By virtue of this arrangement, it will be noted that a defective ballast can be safely and readily replaced in a lighting fixture, even if the circuit of the lighting fixture is energized. To replace a defective ballast, the cover plate 34 is removed and the mounting plate 52, together with the ballast 48 and male plugs 58, 58 secured thereto, is withdrawn from its FIG. 2 position through the access opening 32 until it is clear of the receptacle 22 as illustrated in FIG. 3, the male plugs 58, 58 disengaging the female sockets 46, 46' to break the circuit of the lighting fixture 20. A new ballast 48, also mounted on a mounting plate 52 with male plugs 58,, 58', is then installed in the lighting fixture 20 through the access opening 32 by sliding the side edge portions 54 of the mounting plate 52 into the grooves provided by the retaining plate flanges 42, the male plugs 58, 58 engaging the female sockets 46, 46 to again energize the circuit of the lighting fixture 20. It will be noted that this replacement operation does not require the disconnection or reconnection of any electrical wires, and it can therefore be performed by ordinary maintenance personnel having no experience in electrical work. Moreover, the only disassembly of the lighting fixture 20 is the removal of the cover plate 34 and the attaching screws 36 therefor. However, in the preferred embodiment of the present invention, a precautionary measure is taken to insure that the mounting plate 52 is securely held in place within the receptacle, and this measure includes the provision of a vertical wall 64 formed at the front edge of the mounting plate to have a lengthwise extent that disposes the end portions of the wall 64 adjacent corresponding vertical walls 66 formed on the retaining plate 38 whereby screws 68 can be used to secure the mounting plate 52 thereat. This arrangement, if used, will slightly increase the time necessary to disassemble and reassemble the lighting fixture 20, but it will also provide a safeguard, in addition to the cover plate 34, for maintaining the mounting plate 52 at a proper position within the receptacle 22.

In some types of lighting fixtures to which the present invention is applicable, the voltage at the high voltage side of the ballast is substantial, for example, 785 volts, and, as a result, a potentially dangerous situation may be presented by the possibility of current arcing at the high voltage contact of the male plugs 58, 58 and the female sockets 46, 46', respectively, when the high voltage circuit 62 is made, or broken, during installation and removal of the mounting plate 52. To eliminate this potentially dangerous situation, the present invention provides a unique arrangement which assures that the high volt' age circuit 62 will be broken after the low voltage circuit 60 is broken, and will be made before the low voltage circuit 60' is made whereby the respective high voltage contacts of the male plugs 58, 58 and the female sockets 46, 46 will always be engaged and disengage d while the lighting fixture circuit is open at the respective low voltage contacts therein.

This unique arrangement is best illustrated in FIGS. 6 and 7 where one of the male plugs 58 and a complemental female socket 46 is shown, but it is to be understood that each two part connector unit would be similarly constructed. The male plug 58 has a pair of extending blades 70, 72 of substantially equal length, the blade 70 being generallyflat and being wired to the high voltage side of the ballast 48 (FIG. 8) to form the high voltage contact of the male plug 58, while the blade 72 has a generally U-shaped configuration and is wired to the low voltage side of the ballast 48 to form the low voltage contact of the male plug 58. The female socket 46 has a pair of blade receiving slots 74, 76 which contain, respectively, a high voltage contact 78 wired to the high voltage side of one of the lamps 24 and a low voltage contact 80 wired to the low voltage side of the lamp 24 (FIGS. 8), the slot 74 being formed at the blade-receiving end thereof with an opening 82 shaped to receive the flat blade 70 and the slot 76 is likewise formed with an opening 84 shaped to receive the U-shaped blade 72, whereby the female plug slots 74, 76 will receive only the male plug blade which will connect, respectively, the high voltage contact 70, 78 and the low voltage contacts 72, 80. As best seen in FIG. 7, each of the slots 74, 76 is provided with locating grooves 86 that receive edge tabs 88 extending integrally from each side of the high voltage contact 78 and the low voltage contact 80, and that thereby locate these contacts with respect to the blade-receiving end of the slots 74, 76. Looking at FIG. 6, it will be noted that the tabs 88 are arranged to dispose the low voltage contact 80 at a spacing from the bladereceiving end of its containing slot 76 which exceeds a corresponding spacing of the high voltage contact 78 from the blade-receiving end of its containing slot 78. The contacts 78 and 80 are held in their respective slots 74, 76 by a crosspiece 90 secured in place by a screw 92.

By virtue of this arrangement, when the male plug 58'is caused to engage the female socket 46, as when the mounting plate is being installed in the receptacle 22, the high voltage contacts 70, 78 will be connected prior to the low voltage contacts 72, 80 and this connection sequence cannot result in any current arcing across the high voltage contacts 70, 78 because the lighting fixture circuit will still be open at the disengaged the low voltage contacts 72, 80. Likewise, when the male plug 58 is disengaged from the female socket 46 during removal of the mounting plate 52, the low voltage contacts 72, will be disconnected prior to disconnection of the high voltage contact 70, 78 so that the lighting fixture circuit will be opened before the high voltage contacts 70, 78 are disconnected.

It is to be understood, of course, that it is within the scope of the present invention to obtain a similar result by locating the female plug contacts 78 and 80 at an equal spacing from the blade-receiving ends of the slots 74, 76, and by providing the male plug 58 with a high voltage blade contact 70 of greater length than the low voltage contact 72. Additionally, it is to be understood that while the disclosed embodiment of the present invention electrically connects the male plug 58 to the ballast 48 and the female socket 46 to the lamp 24, the male plug 58 could be connected to the lamp 24, and the female socket 46 to the ballast 48, without departing from the scope of the present invention.

Since the high voltage in the high voltage circuit of some types of lighting fixtures is relatively low (i.e., less than 600 volts), the danger of current arcing at the high voltage contacts of the male plug and the female socket does not pose any problem. Therefore, it is unnecessary to provide the abovedescribed arrangement for connecting and disconnecting the For example, FIG. 9 illustrates a wiring diagram of a rapidstart" lighting fixture which, in accordance with-the present invention, has a ballast 148 arranged to be detachable from the lighting fixture in the same manner as the previously described ballast 48. However, because ofthe wiring connections required in a rapid-start lighting fixture, four pairs of complemental male plugs 158 and female sockets 146 are pro vided as illustrated in FIG. 9. The two right-hand pairs, when engaged, directly connect by lines 160 the high voltage side of the ballast 148 to the high voltage sides of the lamps 124, 124', respectively, and the two left-hand pairs directly connect, respectively, the main circuit lines L, I. to the low voltage side of the ballast 148 and, by lines 160, the low voltage side of the ballast 148 to the low voltage side of. both of the lamps 124, 124'. Thus, just as in the earlier described embodiment, the male plugs 158 and the female sockets 146 will be engaged and disengaged as an incident of installation and removal of the ballast 148.

This invention has been described above for purposes of illustration only and is not intended to be limited by this description or otherwise except as defined in the appended claims.

lclaim:

1. In a fluorescent lighting fixture incorporating a receptacle fitted with a fluorescent lamp means and having electrical line connector means provided therefor including a ballast for operating said lamp means, the improvement comprising a disengageable two-part electrical connector unit interposed in said electrical line connector meanswith one connector unit part fixed in relation to said receptacle and the associated connector unit part associatedwith said ballast, said electrical line connector means including a high voltage circuit and a low voltage circuit for imposing high and low voltages on said lamp means, each of said connector unit parts including at least one pair of contacts, one contact of each of said pairs become engaged prior to said low voltage contacts during said installation of the ballast, and to become disengaged subsequent to disengagement of said respective low voltage contacts during said removal of the ballast.

2. In a fluorescent lighting fixture, the improvement defined in claim- 1 and further characterized in that said connector unit parts consist of a male plug and a complemental female socket, said male plug having two blades of substantially equal length forming one of said pairs of electrical contacts, and said female socket having two blade-receiving slots containing the other of said pairs of electrical contacts with the low voltage contact thereof having a spacing from the blade-receiving end of its slot which exceeds a corresponding spacing of the high voltage contact thereof.

3. in a fluorescent lighting fixture, the improvement defined in claim 2 and further characterized in that said male plug connector blades have different configurations, and in that each of said female plug slots is shaped to receive only the male plug blade which will connect, respectively, the high voltage contacts and low voltage contacts of said pairs of electrical contacts, I 

1. In a fluorescent lighting fixture incorporating a receptacle fitted with a fluorescent lamp means and having electrical line connector means provided therefor including a ballast for operating said lamp means, the improvement comprising a disengageable two-part electrical connector unit interposed in said electrical line connector means with one connector unit part fixed in relation to said receptacle and the associated connector unit part associated with said ballast, said electrical line connector means including a high voltage circuit and a low voltage circuit for imposing high and low voltages on said lamp means, each of said connector unit parts including at least one pair of contacts, one contact of each of said pairs being interposed in said high voltage circuit and the other contact of each of said pairs being interposed in said low voltage circuit, said respective high voltage contacts being arranged to become engaged prior to said low voltage contacts during said installation of the ballast, and to become disengaged subsequent to disengagement of said respective low voltage contacts during said removal of the ballast.
 2. In a fluorescent lighting fixture, the improvement defined in claim 1 and further characterized in that said connector unit parts consist of a male plug and a complemental female socket, said male plug having two blades of substantially equal length forming one of said pairs of electrical contacts, and said female socket having two blade-receiving slots containing the other of said pairs of electrical contacts with the low voltage contact thereof having a spacing from the blade-receiving end of its slot which exceeds a corresponding spacing of the high voltage contact thereof.
 3. In a fluorescent lighting fixture, the improvement defined in claim 2 and further characterized in that said male plug connector blades have different configurations, and in that each of said female plug slots is shaped to receive only the male plug blade which will connect, respectively, the high voltage contacts and low voltage contacts of said pairs of electrical contacts. 